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Rescinded Date:
February 22 , 2016
Remediation and Redevelopment Division
RESCISSION OF POLICY AND PROCEDURE
Subject: Operational Memorandum No. 4:
Attachment 9- In Situ Remedial Discharges
Program Name: Part 201 , Environmental
Remediation and Part 213, Leaking Underground
Storage Tanks of the Natural Resources
Environmental Protection Act, 1994 PA 451 , as
amended.
Number:
Page:
Operational Memorandum
1 of 1
RRD-4, Attachment 9
DEPARTMENT OF
ENVIRONMENTAL QUALITY
Category:
D Internal/Administrative
D External/Non-Interpretive
~ External/Interpretive
Type:
D Policy
D Procedure
~ Policy and Procedure
The Remediation and Redevelopment Division (RRD) Operational Memorandum No 4,
Attachment 9- In Situ Remedial Discharges, dated December 2008 is rescinded. The
information contained in this former Operational Memorandum Attachment has been
reformatted as In Situ Remediation Resource Materials. The resource material is available to
staff and the public as reference documents for In Situ response activities or corrective action
proposals regulated by Part 201 , Environmental Remediation, and Part 213, Leaking
Underground Storage Tanks, of the Natural Resources and Environmental Protection Act, 1994
PA 451, as amended .
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eputy Director
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EQ01 07 (04/2015)
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Remediation and
Redevelo
Interim Final - December 2008
This interim final document takes effect immediately and is to be used as guidance when
conducting response activities under Part 201 and Part 213. The MDEQ w ill take comments via
email and postal mail on this interim final document through June 30, 2009. After comments have
been reviewed , the document will be revised in response to those comments and issued as final.
RRD OPERATIONAL MEMORANDUM NO.4
SITE CHARACTERIZATION AND REMEDIATION VERIFICATION
ATTACHMENT 9 -IN SITU REMEDIAL DISCHARGES
Acronym s and key definitions for term s used in t his d ocument :
NREPA:
Part 22:
Part 31:
Part 201:
Part 213:
MDEQ:
RRD:
U.S. EPA:
Biologic Degradation:
Chemical Degradation :
Criteria or Criterion:
Discharge:
Exacerbation :
Facility:
FAR:
Feasibility Study:
In situ Remediation :
The Natural Resources and Environmental Protection Act,
1994 PA 451 , as amended
Part 22, Groundwater Quality Administrative Rules
promulgated pursuant to Part 31 of NREPA
Part 31, Water Resources Protection, of NREPA
Part 201, Environmental Remed iation , of NREPA
Part 213, Leaking Underground Storage Tanks, of NREPA
Michigan Department of Environmental Quality
Remed iation and Redevelopment Division
United States Environmental Protection Agency
Any process that acts to degrade a contaminant partially or
completely as a result of biological activity. Also know n as
"bioremed iation"
Any chemical alteration (e.g., oxidation, reduction , chelation,
precipitation ) w hich results in a reduction in the mass, mobility,
and/or toxicity of a contaminant
Includes the cleanup criteria for Part 201 of NREPA and the
Risk-Based Screening Levels as defined in Part 213 of
NREPA and R 299.5706a(4)
As defined in R 323.2201 (i) of the Part 22 Rules of NREPA
As defined in Section 20101 of NREPA
Includes "facility" as defined in Part 201 of NREPA and "site"
as defined in Part 213 of NREPA
Final Assessment Report as defined in Section 21311 a of
NREPA including a corrective action plan developed under
Section 21309a of NREPA
Includes "feasibility study" as defined in Section 20101 of
NREPA and "feasibility analysis" as the term is conventionally
used in Section 21311 a(1)(c) of NREPA ;for the purpose of
this document, the term also refers to the overall process for
the evaluation and selection of response actions
A course of action that is designed to meet remedial objectives
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
In situ Remedial Strategy:
In situ Remedial Discharge:
Pilot Study:
RAP:
Remed iation Plan:
Response Actions:
A course of action that is designed to meet remedial objectives
via the reduction of soil and/or groundwater contaminant
concentration or mass in place by the use of any of the
following chemical , physical, or biological processes: (1) The
application of any material (liquid, solid, or gas) or combination
of materials that ultimately results in the direct chemical
degradation of contamination into less toxic or otherwise nontoxic products (e.g., chemical oxidation); (2) The physical
removal or reduction of contaminant mass that utilizes the
application of a material that physically or chemically interacts
w ith soil or groundwater contamination in a manner that
facilitates the removal or reduction in contaminant mass (e.g.,
product recovery utilizing surfactants); (3) The application of
any material or biological organ ism that stimulates, enhances,
or otherwise fosters "natural" processes that degrade
contamination into less toxic or otherwise non-toxic products
Any direct or indirect discharge of a material (liquid, solid, or
gas) into the groundwater or onto the ground for the purposes
of an in situ remed iation
A component of a feasibility study (or feasibility analysis) that
comprises the physical methods and data interpretation used
to assess the performance of a remedial technology or
strategy (or a specific component of such), typically for the
purpose of: (1) Determining the potential efficacy of a
remediation technology; (2) Technology comparison and/or
selection; and/or (3) Establishing remedial design parameters.
Includes "focused feasibility studies," bench and field scale
pilot studies, and may also include pre-operational pilot studies
using a full scale remediation system infrastructure
Remed ial Action Plan, as defined in Section 20101 of NREPA
Includes "remedial action plan" as defined in Part 201 of
NREPA, and "corrective action plan" and "final assessment
report" as defined in Part 213 of NREPA
Includes "response activities" as defined in Part 201 of
NREPA, and "corrective action" as defined in Part 213 of
NREPA
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
2 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
TABLE OF CONTENTS
1.0
PURPOSE AND SCOPE .. ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... . 5
2.0
INTRODUCTION .... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... . 6
3.0
COMMON IN SITU REMEDIAL TECHNOLOGIES .. ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... .. 6
4 .0
GEN ERAL REQU IR EM ENTS AND CONSID ERATIONS ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... ... .. .. 7
5.0
S ITE CHARACTERIZATION AND CONCEPTUAL S ITE MODEL .... .. ... ... ... .. ... ... .. ... ... .. ... . ?
5.1
5.2
5.3
5.4
5 .5
6.0
DELINEATION .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. .. 8
SOURCE AREA C HARACTERIZATION .. .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... 9
GEOLOGICAL AND H YDROGEOLOGICAL C HARACTERIZATION .. .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. 10
GEOCHEMICAL, B IOGEOCHEMICAL, AND B IOLOGICAL CHARACTERIZATION .... .. ... ... .. ... ... .. .. 11
EXPOSURE PATHWAYS, TRANSPORT MECHANISMS, AND RECEPTORS .. .. ... ... .. ... ... .. ... ... .. .. 12
REMED IA L EVALUATION, S EL E CTION , AND DESIGN CONS ID ERATIONS ... ... .. ... ... . 13
6.1
0BJECTIVES ... ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. 14
6.2
P ILOT STUDIES .. ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... .. 15
6.2.1 Bench Scale Pilot Studies .. ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 16
6.2.2 Field Scale Pilot Studies .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 17
6.2.3 Pre-operational Pilot Studies Using Full Scale Remediation System Infrastructure .17
6.3
FEASIBILITY STUDY REQUIREMENTS .. .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... . 18
6.4
CONTAMINANT PLUME AND M IGRATION PATHWAY CONTROL. ... ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. 18
7.0
MON ITORING REQU IR EM ENTS ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... . 19
7.1
PURPOSE AND OBJECTIVES .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... . 20
7 .1.1 Assuring Protection of Public Health, Safety, and Environment ... ........ ........ ........ .... 20
7 .1.2 Evaluating Remedial Integrity and Effectiveness ......... ........ ........ ........ ........ ........ ..... 20
7.1.3 Assuring that Action Levels are not Exceeded at Compliance Monitoring Points .. ... 20
MONITORING P HASES ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. .. 20
7.2
7.2.1 Baseline Monitoring ... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 20
7.2.2 Co-implementation Monitoring ... ........ ......... ........ ........ ........ ........ ........ ........ ........ ...... 21
7.2.3 Post-implementation or Remedial Evaluation Monitoring .... ........ ........ ........ ........ ..... 21
7.2.4 Compliance Monitoring ...... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 21
7.3
ENVIRONMENTAL MEDIA AND COMMON MONITORING PARAMETERS .. .. ... ... .. ... ... .. ... ... .. ... .. 22
7.3.1 Soil Gas .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ......... ........ ....... 22
7.3.2 Indoor Air and Enclosed Spaces ......... ........ ........ ........ ........ ........ ........ ........ ........ ...... 22
7.3.3 Ambient Air ....... ........ ........ ........ ........ ........ ........ ........ ......... ........ ........ ........ ........ ....... 23
7.3.4 Groundwater ..... ........ ......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 23
7.3.5 Soil .... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ 24
COMMON MONITORING PARAMETERS .... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... .. ... ... ... .. . 24
7.4
7.4 .1 Contaminants of Concern and Daughter Products ...... ........ ........ ........ ........ ........ ..... 24
7.4.2 Geochemical and Biochemical Parameters ........ ........ ........ ........ ........ ........ ......... ..... 25
7.4.3 Biological Parameters ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 25
7.4 .4 Physical Parameters .. ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 25
7.4 .5 Discharge Constituents ...... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ....... 26
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
3 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
8.0
APPLICABILITY OF AND COMPLIANCE WITH THE PART 22 RULES ..... ........ ........ .... 26
9.0
DOCUMENTATION REQU IREMENTS FOR OBTAINING A PERMIT EXEMPTION ... ... 26
10.0
MISCELLANEOUS RECOMMENDATIONS FOR DOCUMENTATION ....... ........ ........ .... 28
11 .0
SUBMIITALS REQU IRING PRIOR RRD APPROVAL ....... ........ ........ ........ ........ ........ ..... 28
12.0
REFERENCES ......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ......... ........ ....... 30
APPENDIX A- Discharge to a Plume of Contamination Without a Permit ..... ........ ........ ........ .... 31
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
4 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
1.0
PURPOSE AND SCOPE
The purpose of this document is to provide general direction and requirements for the selection,
design, implementation, and evaluation of in situ remedial technologies and discharges. This
guidance provides the MDEQ's evaluation of what information is necessary to support the
selection of an in situ remedy. It is intended to foster the development of viable strategies that
are consistent w ith the requirements of Part 201, the Part 201 Administrative Rules, Part 213,
and the Part 22 Rules, as applicable.
This document also describes the applicability of the Part 22 Rules to in situ remed ial
discharges and general requirements for obtaining a permit exemption pursuant to
R 323.221 O(u)(ii and iii). The direct or indirect introduction of ANY SUBSTANCE into
groundwater that meets the definition of a discharge is subject to the standards of the Part 22
Rules. As such, the standards of the Part 22 Rules apply to ALL in situ remedial discharges.
This document provides acceptable approaches and ranges of appropriate assumptions that are
intended to support consistent exercise of professional judgment in a manner that produces
satisfactory outcomes. Alternative approaches may be used if the person proposing the
alternative demonstrates that the approach meets all the requirements of the statute and rules.
With the variety of established and developing in s;tu remed ial technologies and a myriad of
facility-specific applications, each w ith its own unique combination of circumstances and
nuances, it is impossible to cover every scenario. However, commonly encountered scenarios
are provided as examples to illustrate conceptual approaches where appropriate . Nevertheless,
this document is not intended to be comprehensive, nor should it in any way be construed as a
"how to" manual. Similarly, it is not intended as a substitute for valid scientific or technical
references or direct experience and lessons learned from emerging or established technologies.
Rather, it focuses primarily on the general process and considerations for selection, design,
implementation, and evaluation of in situ remedial strategies. It is intended that this document
w ill lead to a more comprehensive and systematic approach to in situ remediation, which in turn
w ill promote the appropriate application of such technologies, or otherwise help to avoid the
pitfalls of implementing remedies that have little or no chance for success.
This document is intended solely as guidance to foster consistent application of Part 201 and
Part 213 of NREPA and the associated Administrative Rules. This document does not contain
any mandatory requirements, except w here requirements found in statute or administrative rule
are referenced. This guidance does not establish or affect the legal rights or obligations for any
of the issues addressed . This guidance does not create any rights enforceable by any party in
litigation with the MDEQ. Any regulatory decisions made by the MDEQ in any matter addressed
by this guidance w ill be made by applying the governing statutes and Administrative Rules to
the relevant facts.
This guidance is based upon the requirements found in Part 201, Part 213, and Part 31 of
NREPA and the rules promulgated thereunder. In addition to the requirements and rules of the
NREPA, in s;tu injections must also be compliant with the U.S. EPA Class V injection well
requirements. For further information on the Class V injection well requirements, refer to
http://www.epa.gov/safewater/uic/class5/basicinformation.html.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
5 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
2.0
INTRODUCTION
The RRD supports and encourages the use and development of innovative remedial
technologies, including in situ remediation . These technologies are commonly employed at
contaminated facilities in Michigan, especially at petroleum contaminated leaking underground
storage tank sites and facilities with chlorinated solvent releases.
In situ remedial technologies are often viewed as less costly, more effective, or otherwise more
practical than ex situ cleanup methods such as groundwater pump-and-treat or soil excavation
and disposal (or treatment). Although this contention is often true, in situ remedial technologies
are not universally appropriate, nor do they render ex situ remedies obsolete. Rather, both in
situ and ex situ methods are effective, depending on the facility-specific characteristics and the
nature of the application . Often a synergistic remedial effect can be attained by using a
combination of methods, such as ex situ methods to address grossly contaminated source soils
or groundwater followed by in situ methods to provide for accelerated degradation of residual
dissolved-phase contamination.
The efficacy or cost effectiveness of any remedial course of action at a particular site, w hether
in situ or otherwise, is determined by the amenability or limitations posed by a number of
application-specific variables. These include the nature, mass, and distribution of the
contamination, geological and hydrogeological complexity, geochemical and biochemical
makeup of the contaminated media, site infrastructure, precision and detail of site
characterization, or vulnerability of receptors. In situ technologies in particular tend to be
sensitive to these variables, and therefore, may provide much less certainty in the outcome than
other remedial approaches. Further, most in s;tu technologies have the potential to result in
unintended effects resulting from the chemical reactions or biological processes involved .
Since this multi-faceted nature is inherent with most in situ technologies, thorough evaluation
and planning are warranted to ensure that the selected technology is appropriate for the
application; is implemented and monitored in an effective manner; has a reasonable chance for
success; and can be implemented in a manner such that unintended effects from remedial
processes can be reliably identified and controlled . Without such evaluation and planning, an
otherwise effective technology is likely to have limited effectiveness in application , or may prove
to be ineffective altogether.
3.0
COMMON IN SITU REMEDIAL TECHNOLOGIES
The following are some of the more commonly used in situ technologies that involve discharges
and to which this document applies:
•
•
•
Chemical Oxidation
hydrogen peroxide/Fenton's Reagent
ozone sparging
potassium or sodium permanganate
sodium persulfate
Air Sparging
Enhanced Bioremediation
Introduction of oxygen as an electron acceptor (e.g., oxygen sparging or oxygen
releasing compounds)
Introduction of anaerobic electron acceptors (e.g., sulfates)
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
6 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
•
•
4.0
Bioaugmentation
Enhanced reductive dechlorination
Surfactant Injection with Non-aqueous Phase Liquid Recovery
Permeable Reactive Barriers
GENERAL REQUIREMENTS AND CONSIDERATIONS
A FAR, RAP, or pilot study (as part of a feasibility study) that proposes in s;tu remed iation as a
remedial option must contain the following general items, as appropriate to the facility-specific
circumstances:
•
•
•
•
Presentation of Site Characterization Data, Data Evaluation, and Conceptual Site Model
Technical Basis for the Selection of the In Situ Remedial Strategy (Based on Site
Characterization and Conceptual Site Model)
Comprehensive Description of the Remedial Design, including:
Remed ial objectives
Design and construction plans
Operational parameters
Implementation schedule
Contingency plans
Comprehensive Monitoring and Evaluation Plan, including:
Environmental media that will be monitored
Monitoring parameters
Monitoring locations
Monitoring schedule
Specification of parameter thresholds and/or criteria that define remed ial failure or
success
Specification of parameter thresholds and/or criteria that will trigger the
implementation of further response actions and/or contingency plans
Reporting schedule
Additional discussion of these general FAR, RAP, and pilot study requirements follows.
5.0
SITE CHARACTERIZATION AND CONCEPTUAL SITE MODEL
The foundation for the selection of any remedial technology for further evaluation, pilot studies,
or full scale implementation is site characterization . Ultimately, successful in situ remediation
begins w ith sufficient site characterization to make informed and thoughtful decisions in the
selection and design of a remedial strategy.
The development of a conceptual site model is an important part of the site characterization
process, and a particularly critical component to implementing in situ remediation . A conceptual
site model is the facility-specific qualitative and quantitative description of the migration and fate
of contaminants with respect to possible receptors and the geological , hydrogeological,
biological , geochemical, and anthropogen ic factors that control contaminant distribution . For
implementation of in situ remediation, the conceptual site model also requires a comprehensive
understanding of w hat effects, influences, and interactions may arise as a result of the in situ
remedial processes. The conceptual model expresses an understanding of the facility structure,
processes, interactions, and factors that will or may affect contaminant plume development and
behavior before, during, and after implementation of in situ remediation. It is built upon
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
7 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
assumptions and hypotheses that have been evaluated using facility-specific data and are
continually reevaluated as new data are developed throughout the facility life cycle .
Generally, full scale implementation requires comprehensive site characterization, meaning that
the extent of contamination is fully delineated, source contamination is well characterized , the
geological and hydrogeological conditions are thoroughly understood, all transport mechanisms
and exposure pathways have been evaluated, and all receptors have been identified. Interim
responses, pilot studies, or smaller scale applications may warrant less comprehensive
characterization prior to evaluation or implementation, depending on the remed ial objectives,
the nature of the technology, and the facility-specific circumstances.
At a minimum, the level of site characterization must be sufficient to demonstrate that the
proposed in situ remedial strategy is appropriate for the site conditions, whether part of a pilot
study, interim response, or full scale cleanup. This does not mean that the level of site
characterization has to support a definitive conclusion as to the efficacy of a remedy, but rather
it must support that the technology has a reasonable chance for success in the application.
Further, beyond a minimum effort needed to demonstrate that a technology is appropriate for a
site, there is also a cost benefit balance to consider between the expense of increasing
precision and detail in site characterization and the benefit those provide in terms of reducing
the costs or hazards associated with the remedial technology. In many cases, extra effort in site
characterization can facilitate a more focused and effective remed ial approach, w hich is likely to
reduce the magnitude of the remedial effort needed to meet the intended remedial objectives for
a facility.
The following discusses the various aspects of site characterization as applicable to an in s;tu
remediation:
5.1 Delineation
For implementation of full scale in situ remediation or in situ remed ial discharges that are
otherwise part of a final remedy associated with a FAR or RAP, the extent and distribution of
contamination in the soil and groundwater should be defined both vertically and horizontally.
For groundwater monitoring, this usually warrants permanent monitoring wells as a means to
ensure that the vertical and horizontal extent of the contamination remains delineated during
and after the implementation of any in situ remedial discharge.
In cases w here the existing delineation is very broad, it may sometimes be necessary to more
narrowly define the extent of contamination , both from a cost benefit as well as from a public
health and safety and environmental protection standpoint. An example of where the latter
would apply is a facility that has receptors located proximal to the defined extent of the
contamination such that these receptors would be immediately threatened by plume expansion.
In such circumstances, more precise delineation is needed prior to initiating the in situ remedial
discharge to define a larger "buffer zone" around the contaminated area as a means to ensure
the timely protection of vulnerable receptors. Note that where more precise delineation is
needed prior to implementing an in situ remedial discharge, it may, in some circumstances, be
appropriate to complete the additional delineation in the context of a FAR or RAP
implementation, rather than prior to the development of a FAR or RAP.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
8 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
For in situ remedial discharges that are part of a pilot study or interim response activity, the
degree of comprehensiveness of site characterization that is warranted depends on the nature
of the discharge in light of the facility-specific circumstances and conditions. Some of the
factors to consider in evaluating whether the level of delineation is appropriate for a discharge
include: (1) The volume and rates of the discharge; (2) Contaminant concentrations, including
the presence of grossly contaminated media; (3) The distribution of contamination relative to
receptors; and (4) Proximity of the discharge to receptors.
It is generally necessary to achieve comprehensive delineation prior to implementing a pilot
study or interim response action. However, in some circumstances it may be appropriate to
implement an in situ remedial discharge without completing comprehensive delineation. For
example, this is often appropriate where an in situ remedial discharge is used as a barrier to
protect a specific receptor or to prevent the longitudinal expansion of a contaminant plume.
Similarly, in situ treatment of source contamination may also be appropriate as an interim
response in certain circumstances if the area surrounding the discharge is otherwise well
characterized.
5.2 Source Area Characterization
If an in s;tu remedy is intended to treat contaminant "source" areas or "hot spots" (e.g., any area
containing or likely to contain anomalously high contaminant concentrations, free-phase
hydrocarbons, or free product), or if the in situ remedial discharge w ill incidentally take place in
an area where such levels of contaminants may be present, the source area must be well
characterized prior to conducting the remedial discharge. This includes both the identification of
maximum contaminant concentrations and the vertical and horizontal extent of such areas.
Note that where applicable, source characterization includes the characterization of
contamination that may be present in saturated zone soils (e.g., adsorbed non-aqueous phase
liquids or "smear zone" contamination ).
Thorough source area characterization is important for several reasons. First, the presence of
high contaminant concentrations has implications with regard to whether or not an in situ
remedial discharge can be conducted in a manner that does not result in unacceptable
exposures, exacerbation of contamination, or fire and explosion hazards (as applicable to the
contaminants of concern). This is especially true where the treatment of heavily contaminated
media is implemented in close proximity to vulnerable receptors such as buildings, utilities, or
surface water bod ies that could be affected as a result of dimensional, chemical, or physical
changes of the contamination or contaminated media brought about by an in situ remedial
discharge.
Second, source area characterization is a critical component to estimating contaminant mass,
w hich in turn is needed as part of pred icting the scale of a remedy that will be needed to reach
the intended objectives. Without this type of estimation , it is impossible to know w ith any level
of certainty what type of remed ial approach is likely to be the most cost effective for any
particular site or facility.
Third, source area characterization fosters a more targeted approach . With in situ remedies in
particular, a targeted approach toward mitigating source contamination is likely to be more cost
effective by reducing the overall amount of remed ial materials needed to reach the intended
objectives. What may be more significant, however, is that minimizing the amount of material
discharged is a primary means to control potential threats to receptors resulting from the in situ
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
9 of34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
remedial discharge. This is especially important when a discharge may involve reactions, such
as exothermic oxidative reactions that are likely to lead to hazardous conditions or may
exacerbate contamination. From a cost effective standpoint, a judgment has to be made, based
on facility-specific circumstances, as to what level of detail is needed before the economic
benefits of a targeted approach no longer offset the costs of obtaining add itional detail in source
area characterization .
In many cases, source area characterization is likely to reveal it to be much more practical and
cost effective to implement a non-in s;tu remedy in conjunction with or in lieu of in situ
remediation. For example, after consideration of contaminant mass estimates and remedy
costs, along with the associated risks and uncertainty in efficacy, it is often much more efficient
and practical to implement source treatment via another means, such as excavation, and to
mitigate residual groundwater contamination via in s;tu technologies.
5.3 Geological and Hydrogeological Characterization
The geological and hydrogeological conditions must be thoroughly characterized and evaluated
w ith respect to how those conditions affect contaminant transport and migration pathways, as
well as the ability to effectively deliver the remedial reagents to the contaminated media. This
includes:
•
•
•
•
•
The demarcation of geological units;
Characterization of the physical characteristics of geologic units (e.g., porosity,
permeability, hydraulic conductivity, hydraulic gradients, groundwater flow rates, etc.);
Identification of confining or semi-confining formations;
The identification of preferential migration pathways; or
Other related factors, as appropriate.
The assessment of these conditions must demonstrate that, in light of the selected technology
and remedial system design, either the geological and hydrogeological conditions are amenable
to the selected technology, or otherwise that impediments caused by these conditions can be
feasibly overcome .
Facilities dominated by geological formations characterized as having low permeability are
difficult to treat via in situ remedial methods due to the inherent resistance of such media to
accepting a discharge. Further, fractures (existing or created as a result of the discharge) or
even minor geological units of a comparatively high permeability are often present. These
structures may serve as preferential pathways that can further inhibit the ability to distribute
remedial material into and throughout contaminated media with low permeability.
Similarly, facilities with intricate or otherwise complex stratigraphy, such as those with
alternating, thinly bedded , and/or discontinuous sand , silt, and clay units, are generally difficult
to remediate with in situ remedial technologies because of the difficulty in distributing remedial
reagents throughout the stratigraphic units intended for treatment. Many of the available in s;tu
remedial technologies utilize reagents that rapidly degrade upon introduction to the subsurface
(some only exist or remain active on the order of minutes, hours, or days after introduction ).
Therefore, where there are zones of varying permeability, treating contamination bound in the
less permeable zones becomes very problematic due to the limited retention times of the
remedial reagents. Whereas the contaminants of concern may have had years or decades to
work their way into the low permeable units, the comparatively short-lived nature of most
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remedial reagents are likely to render them only able to effectively treat the more highly
permeable units or to surficially treat the low permeable units. These situations can potentially
leave continued source med ia after in situ treatment, rendering the treatment virtually
ineffective. That is not to say that obstacles associated w ith complex stratigraphy cannot be
overcome when implementing in situ technologies, but such circumstances generally warrant a
more detailed geological evaluation and a robust remedial design than may otherwise be
necessary to ensure effective implementation .
Although permeable geological formations are generally amenable to in situ remediation, it
should be recognized that even these conditions are not without concerns. First, even when the
geological formation is characterized as having a homogeneous distribution , preferential flow
pathways w ill still exist. Particularly when treating groundwater contamination, these can limit
the ability to distribute the remed ial reagents throughout the targeted media. Although this is
generally much more easily overcome in permeable formations, it still warrants an
understanding of how the geological or hydrogeological conditions will affect the in situ remedial
discharge.
For example, an aqu ifer with an unusually rapid flow rate could present certain problems with
regard to lateral dispersion of remedial reagents, retention times, or even the ability to induce
the necessary geochemical conditions in an aquifer if the in s;tu remed ial discharge is
"overwhelmed" by the rapid influx of untreated groundwater. This could be particularly
problematic for a bioremediation technology such as in situ reductive dehalogenation where the
success of the remedy is contingent upon creating and maintaining an anaerobic environment in
an aquifer. In addition , the presence of any geological variability within an otherwise permeable
and homogenous formation, even if ostensibly minor, can significantly affect the
implementability or success of an in situ remedial approach . For example, if an air sparge
system discharges air below even a very thin clay unit in an otherwise sandy or gravelly
formation , the clay could effectively preclude the upward migration of air through an aquifer
rendering the air sparge system wholly or partially ineffective . In add ition, implementation of this
technology in such conditions could cause vapor or explosion hazards due to lateral migration of
vapors.
5.4 Geochemical. Biogeochemical. and Biological Characterization
As appropriate to the selected remedial technology, the geochemical, biogeochemical, and/or
biological conditions must be thoroughly characterized and evaluated with respect to:
•
•
•
The presence or absence of geochemical, biogeochemical , or biological components or
related parameters that are essential to the function of the remedial technology;
The presence of these components that may, or are likely to interfere with the function of
the remed ial technology; and
Geochemical or biochemical reactions and processes that are likely to occur and the
potential outcome of those reactions or processes, especially those that may generate
incidental or unwanted "side effects."
In almost all cases, this requires the establishment of baseline parameters to assess whether
site conditions are amenable to and appropriate for the selected technology, to determine if
certain supplementation is needed (or practical), and to serve a means by which to gauge or
evaluate aspects of the remedial technology during implementation.
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Most in situ remedial technologies involve considerable and often complicated chemical or
biochemical interaction between the reagents and/or biological agents used in the remedial
process and various geochemical, biogeochemical , or biological components of the treated
environmental media.
For some technologies, the presence of certain constituents in the environmental media and the
resulting chemical or biochemical interaction is a critical and integral part of the remed ial
process. For example, the success of enhanced bioremediation depends on the presence of
the heterotrophic microorganisms that are capable of either directly or co-metabolically
degrading the contaminants of concern and subsequent daughter products. These microbes
must also be able to thrive in sufficient quantities to achieve the desired rates of degradation,
w hich in turn is heavily dependent on the presence of certain electron acceptors (oxygen , ferric
iron, manganese, nitrates, sulfates, etc. ), and food and nutrient sources as part of the energy
cycle that supports microbe populations. Therefore, the design of a bioremedy must consider
w hether the right types or species of microbes are already present, or if microbe populations
must be supplemented , and whether the right biogeochemical conditions are present to support
microbe populations.
Similarly, Fenton's Reagent is an oxidation remedy that requires the availability of sufficient
quantities of ferrous iron, whether naturally occurring or supplemented, to catalyze the desired
chemical oxidation reaction . Therefore, evaluation of this type of remedy should consider
w hether sufficient concentrations of dissolved iron are present or if they can otherwise be
practically supplemented.
Most in situ remediation technologies also involve chemical or biochemical processes that are
largely incidental and undesired because the reactions either impede the ability of the in situ
remedial technology to degrade or remove contamination, or may otherwise generate certain
"side effects" from the remedial processes. The primary reason for the former is the fact that
certain remedial reagents, oxidants in particular, do not selectively react with the contaminants
of concern. Rather, they w ill readily react with a number of naturally occurring materials
including metals, organic materials, or inorganic carbon. In the case of oxidants, these
materials scavenge the oxidant, thereby increasing the amount of oxidant needed to achieve the
remedial objectives, perhaps to the point that naturally occurring materials become the primary
driver behind the amount of oxidant needed. The potential "side effects" from in situ reactions
can include the generation of explosive gases from the chemical or biochemical reactions, the
leaching of metals from soils due to changes in redox conditions resulting from chemical or
biochemical processes, or even the impact to certain receptors due to the incomplete
consumption of remedial reagents or incomplete breakdow n of certain contaminants. All of
these factors must be assessed prior to implementation to determine whether the remedy is
likely to be practical, whether potential side effects are likely to be generated, and most
importantly, whether they can be effectively monitored and controlled.
5.5 Exposure Pathways. Transport Mechanisms, and Receptors
In no case is it appropriate to implement an in situ remed ial discharge without first having
conducted a thorough assessment of exposure pathways, transport mechan isms, and the
impact to all potential receptors. This includes identification of any and all infrastructure or
features on or near a facility that have the potential to become impacted due to the discharge.
These may include: buildings, utilities (especially sewers, man-ways, or any other sub-grade
enclosed spaces), water recovery wells, or surface water bodies. This assessment also
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includes comprehensive identification of any preferred migration pathways that could result in
the impact to receptors.
6.0
REMEDIAL EVALUATION, SELECTION, AND DESIGN CONSIDERATIONS
The evaluation, selection, and design of in situ remedial strategies must utilize a systematic and
logical approach, based on facility-specific conditions and attributes of available remedial
alternatives to determine what remed ial strategy (which may include more than one remedial
technology or method ) is most appropriate for a site. This may warrant successive levels of
evaluation before a conclusion can be reached as to what remedial strategies are appropriate or
how they are best implemented . Such levels may include initial conceptual and cost analysis,
bench and field scale pilot stud ies, and finally a detailed feasibility study (based on site
characterization and results of the pilot study).
The level of effort and detail that is warranted in evaluating remedial alternatives depends on
facility-specific circumstances, how well established and effective the remedial alternatives are
(in similar applications), and the general level of confidence as to the efficacy of the remedy. In
some circumstances, there may be obvious choices as to what remedy is likely to provide the
most cost effective and practical solution and which may not warrant comprehensive pilot
studies prior to proceeding toward full scale implementation . In other circumstances, extensive
evaluation may be warranted in order to determine the best remedial option .
Regardless of what level of evaluation is warranted , the selection of any in situ remedial
technology for a pilot study or full scale implementation must be based on the facility-specific
conditions and the attributes of potential remedial alternatives w ith respect to those conditions.
This means that there has to be sufficient site characterization to show that site conditions are
amenable to the selected remedial technology, and that the technology can be implemented in a
pred ictable manner. This also means that there has to be enough known about the facility to
allow the remedial design to be "tailored" to the site, either to optimize the remedy, reduce the
risks to receptors, and/or to otherwise overcome remedial barriers presented by facility-specific
conditions.
The RRD often sees in situ remediation and remedial discharges implemented in an ad hoc and
generic fashion, with little consideration given to facility-specific variables and little planning, and
sometimes with little or no site characterization. Such approaches generally do not lend
themselves to cost effective remediation over the long-term because they generally do not work,
even after several different methods may have been "tried out" at a particular site. This is
because the success of a remedy rests not only on whether a particular technology has
potential for success; rather, selection and implementation of a remedial technology according
to site conditions is much more critical to the success of any remedial strategy.
In many cases, existing site infrastructure (such as previous remediation system components)
has been utilized in the design of in situ remediation systems. This sort of "recycling" often
limits the effectiveness of a system because the components end up being used for something
that they were not designed for, which in turn can result in incomplete remediation of a
contaminated area or interval. There have also been circumstances w here critical monitoring
wells were used as treatment wells. This approach leads to ineffective remediation because the
design of a proper monitoring well network is much different than what would be desired for a
properly designed treatment well network. Further, the use of mon itoring wells in this way
leaves virtually no means to determine whether an in situ remedial discharge has been even
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marginally effective in reducing contaminant concentrations. This is because subsequent
samples from treatment wells are not representative of the treatment~- Rather, they are
representative of w hat may be a small and localized volume of treated groundwater at a discrete
treatment location.
In addition , while there are a number of excellent and very reputable in situ remedial products
and remedial service providers available, some manufacturers and service providers make
exaggerated or erroneous claims about their products or processes. For example, claims are
often made that a particular product or technology is effective in just about any set of conditions,
including facilities with very low permeability (often claiming a very large radius of influence in
formations with very low permeability) or complex stratigraphy alike. Often these claims are of
an anecdotal, hypothetical, or presumptive basis, or otherwise based on case studies that are
not really designed to show whether a technology is effective, but rather, massaged to show a
specific outcome. This is not to say that such remedial technologies are ineffective, but contrary
to such claims, there is no single remediation technology that works unequivocally well in all
applications. Again , the success or failure of any particular remedial technology usually has
less to do with the technology itself than how the technology or remedial strategy is
implemented at a facility.
Further, the design of an in s;tu remedial strategy should ensure that the remedial discharge will
not compromise the structural integrity of important infrastructure such as underground storage
tanks, product lines, or natural gas lines. Note that discharging oxidants or other items of a
corrosive nature in the vicin ity of certain utilities or product storage and dispensing systems is
generally not appropriate .
The following include some general considerations for implementation of an in situ remed iation:
6.1 Objectives
The RRD considers the definition of the overall remedial objectives for a facility and the
objectives for each major component of a remedial strategy to be an important step in the
remedial process because it facilitates a systematic and logical approach to remedial
evaluation, selection, and design. Objectives for bench and field scale pilot stud ies should also
be defined. Note that the RRD considers the definition of remed ial objectives necessary as part
of determining whether an in situ remedial strategy is appropriate, and in turn , determining
w hether a FAR or RAP meets the requirements of Part 213 or Part 201 of NREPA.
For example, the RRD would not generally approve or endorse a FAR or RAP (or an in situ
remedial discharge proposed therein) that is designed to treat groundwater contamination if it
does not also contain provisions to address grossly contaminated source med ia. The rationale
for this position is that the overall objective of a FAR or RAP is to present a final remedy to
address all exposure pathways. Treating one component but not the other in this circumstance
would not fully address the groundwater pathway, and therefore, is not consistent with the
objectives of a FAR or RAP. However, the RRD may approve a remedial strategy of that nature
in the context of an interim response if it were appropriately presented as such, w ith the
objective of preventing the further migration of groundwater contamination .
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6.2 Pilot Studies
Pilot studies are particularly important in the evaluation of in situ remedial alternatives because
of the large number of associated variables in field implementation. Virtually all in situ remedial
technologies warrant some level of facility-specific pilot testing prior to full scale implementation
of a remedial discharge.
Pilot studies serve a variety of purposes with the primary objectives being:
•
•
•
Remed ial decision making, including decisions as to whether or not to proceed to the
next level of evaluation or to full scale implementation of an in situ remed ial strategy;
Establishment of remedial design or operational parameters; and
Assessment of remedial "effects," positive and negative.
Each of these general objectives can encompass a number of specific sub-objectives, as
determined based on the facility-specific circumstances. These may include:
•
•
•
Determining estimates of the radius of influence from treatment or recovery locations;
Establishing long-term estimates or projections on the amount of remedial reagents
needed, time frames to complete objectives, etc.; or
Identification of specific problems that may be encountered during system operation,
including problems with permeability, preferred migration pathways, the potential for
secondary discharges, or the potential for exacerbation.
The need for a pilot study is facility or application-specific, but should consider:
•
•
•
•
•
How well established is the remedy in similar applications;
Variables, uncertainties, and complexities at the site that have the potential to affect the
efficacy of the remedy;
The general degree of confidence in the remedy based on facility-specific cond itions and
previous experience or reliable case studies dealing w ith a remed ial alternative in similar
conditions;
The scale of the remedy; and
The potential consequences (from a health, safety, environmental protection, or financial
standpoint) of a failed remedy.
Pilot studies should be carefully designed to provide for objective evaluations of the remed ial
technologies in question. This is critical to ensuring the validity of the results and their utility as
the basis for the design of further investigations or full scale remedial strategies.
When an outside party (including any remedial technology vendor) is retained to conduct any
part of a pilot study (as opposed to completing this work "in house"), the end user should
maintain direct involvement with the design and implementation , as well as the analysis and
review of the results. Often, an outside contractor or vendor will have little if any knowledge of
actual site cond itions. For this and other reasons, the results of these investigations should not
be blindly accepted by the end user. Rather, direct involvement is usually needed to ensure
that the investigation meets the objectives for which it was intended, that the investigation
appropriately represents site conditions, and that the results are reliable . The end user is
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ultimately responsible for any representations made as to the outcome of a pilot study, including
the quality of the data.
Finally, pilot stud ies conducted by neutral or independent parties are preferred over those
conducted by remedial technology vendors. Greater caution should be used when relying on
the results from the latter because some vendors may be prone to be bias toward their own
products. Vendor conducted investigations warrant greater scrutiny than independent
investigations to ensure that the results are reliable; however, all pilot studies warrant careful
scrutiny.
6.2.1 Bench Scale Pilot Studies
Bench scale pilot studies, such as packed column tests, are underutilized in evaluating in situ
remedial alternatives; however, these can serve as a very cost effective screening tool in the
remedial evaluation, selection, and design process. They can be simple and relatively
inexpensive to do, yet can provide a large amount of initial information that can be used to
better optimize field scale investigations or full scale remediation. Moreover, if a remedial
alternative turns out to be impractical or ineffective, it is better to find that out in a bench scale
study than after a relatively greater investment in a field scale study or full scale system.
An example of the benefits from a bench scale pilot study is well illustrated by the results of a
packed column test performed as part of a remedial evaluation for a former plating operation.
The test was used to evaluate the ability of hydrous ferric oxides (HFOs) to bind dissolved nickel
contamination at the facility. Whereas the preliminary evaluation suggested that this method
should be effective, and although the test showed that the HFOs did, in fact, bind lab grade
nickel as predicted, the HFOs would not bind nickel in the groundwater collected from the site.
Based on the results of this test, other remedial options were evaluated. It was later found that
a chelating agent was also present in the contaminated media w hich had the effect of keeping
nickel in a mobile state. In this case, the bench scale study was very beneficial in that it
provided information that would not have been available without a facility-specific evaluation.
Further, it prevented the premature initiation of a field scale study or remediation that would
have proved to be of little or no benefit and at a relatively large expense.
Bench scale investigations should be designed to represent "real world" conditions to the extent
possible. In regard to using bench scale tests to estimate required amounts of remedial
reagents, caution should be used in that bench tests are likely to represent best case estimates
due to the generally more "ideal" conditions associated w ith controlled tests (particularly, the
ability to ensure more even and complete distribution of remedial reagents into the
contaminated med ia, which is not the case with in situ remed ial discharges in practice).
However, such testing can be used to account for the "sum" of all of the reactions or processes
likely to take place between the remedial reagent(s) and the treated media, including primary
and secondary reactions, and reactions w ith all materials (naturally occurring or artificial) that
may be present in the contaminated media. Often it is the facility-specific geochemical
conditions, and not the contaminant mass itself, that is the primary driver behind the quantities
of remed ial reagents needed to reach remedial objectives. Therefore, such testing may often
be a more practical means than stoichiometric analysis or complex modeling to estimate the
minimum quantities of remedial reagents that w ill be required to reach remed ial objectives.
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In regard to identifying potential problems or side effects that may result from the discharge,
bench scale pilot studies may be the most appropriate means for initial evaluation of the
following:
•
•
•
•
•
The potential for the formation of hazardous "daughter" products or other by-products
from in situ reactions;
The potential for the generation or liberation of hazardous or explosive vapors;
The potential for leaching of metals from soils;
The formation of precipitates; or
Problems associated with reaction rates or exothermic heat generation. Such data may
indicate the need for monitoring in field scale investigations or implementation .
Conversely, given a sufficiently designed test, such data may show that certain
monitoring is not warranted or may support reduced monitoring of certain parameters in
field applications.
An additional benefit from bench scale investigations is that they can be designed to provide the
opportunity to directly observe certain remedial processes, which is advantageous in certain
circumstances. For example, in evaluating an in situ technology to mitigate free product, a
bench test could be designed that would allow direct observation of the product; therefore,
provid ing a means to qualitatively assess degradation . A comparative field scale investigation
may not be as conclusive in this regard because it is difficult to distinguish between genuine
degradation from the in situ remedial discharge and natural fluctuations in product levels in
recovery or monitoring wells.
6.2.2 Field Scale Pilot Studies
In practice, it is difficult to pred ict the exact outcome of a remedial discharge with respect to its
effectiveness or whether or not it can be safely implemented. Moreover, once a substance is
discharged , it may be difficult-to-impossible to reverse the process. Therefore, field scale pilot
studies should be conducted whenever the following circumstances arise:
•
•
•
There is an unacceptable degree of uncertainty as to the efficacy of a selected
technology.
The failure of a remedial alternative may result in unacceptable consequences for a
facility, either from a health, safety, environmental protection, or economical standpoint.
Facility-specific performance data is needed to establish design parameters for a full
scale design (e.g ., establishing the radius of influence, discharge rates, recovery rates,
etc.).
Alternatively, in some circumstances, it may be more practical to over design certain aspects of
a system in lieu of field scale pilot stud ies. However, this is not universally appropriate.
6.2.3 Pre-operational Pilot Studies Using Full Scale Remediation System
Infrastructure
The RRD recognizes that in some circumstances it may be more practical and cost effective to
proceed with the installation of a full scale system infrastructure w ithout first conducting a
separate pilot study, and using the full scale infrastructure to conduct the necessary tests. This
may be appropriate for smaller scale efforts where the cost and effort to construct and install a
full scale system infrastructure or even perhaps an "over designed" system may be less
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substantial than the cost and effort associated with a separate pilot study. This may also be
appropriate where there is generally a high level of confidence in the design and integrity of a
remediation system, absent a separate pilot study, based on comprehensive site
characterization data and well established remedial design parameters. However, this does not
in any way preclude the necessity of a proper evaluation prior to proceeding with full scale
discharges.
6.3 Feasibility Study Requirements
Upon completion of any necessary pilot study, a detailed feasibility study should be completed
to compare and evaluate remedial options. For remedial options that included a pilot study,
site-specific data should be incorporated to the extent practical. This will derive more accurate
projections and estimates as to remedial design parameters, pros and cons of the remedial
option, and remedial costs.
6.4 Contaminant Plume and Migration Pathway Control
Any remedial discharge, w hether part of a pilot study or full scale remedy, must be implemented
in a predictable and controlled manner, such that the discharge does not result in unacceptable
threats and exposures to receptors due to the chemical or physical changes resulting from
remedial processes (e.g., vapor migration , explosion hazards, contaminant plume expansion, or
exacerbation, etc.). Although this is achieved , in part, through proper monitoring as a means to
determine w hether such risks may become manifest, engineering and/or procedural
mechanisms are also usually necessary to control these risks, especially where receptors are
located in close enough proximity to a treatment area.
Where there are no receptors present that may be immed iately threatened by the effects of an
in situ remedial discharge, it may be adequate to rely on monitoring with contingency planning
as a means to ensure that there is no risk of increased threat. However, most facilities such as
operational gas stations, active manufacturing facilities, or facilities w ith residential homes in the
area do not fit this type of scenario. Remedial discharges at these facilities may warrant robust
engineering controls for certain in situ remediation technologies.
The following generally describes some of the methods that are often used as part of
maintaining the contaminant plume and migration pathway control:
•
It is often necessary to initiate remedial discharges in an incremental, step-wise fashion
beginning with low volumes, concentrations, or discharge rates, and working up toward
the desired operational parameters. This provides for greater predictability in
determining the effects of a discharge, which is particularly important when highly
reactive reagents are discharged.
•
Discharge volumes and rates should be minimized , to the extent practical, to reduce
plume expansion resulting from the displacement of flu ids. This also prevents
"mounding" of the groundwater table during the discharge, which can spread
contamination (particularly free-phase contamination) vertically or horizontally.
•
Whether discharging gases or liquids, the distribution of a discharge can be used to
prevent the displacement of contamination. One way to do this is to ensure a relatively
even discharge rate over an area that completely encompasses the contaminated media
intended for treatment. An additional level of control that can sometimes be useful is to
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discharge at relatively higher rates around the perimeter of a contaminant plume than in
its interior. Ideally, this will create a small degree of mounding around the outside of a
plume to help hold contamination in place. A similar discharge protocol that may be
practical in some circumstances is an "outside-in" approach where a remed ial discharge
is initiated around the perimeter of the treatment area and then incrementally shifted to
discharge locations toward the interior of a plume . The goal of this method is to
incrementally shrink a contaminant plume.
7.0
•
If a remedial discharge requires the dilution of remedial reagents prior to discharge, it is
often beneficial and practical to use contaminated groundwater from the site for dilution
in order to minimize the net discharge volume. This may not be practical at facilities
w here a reliable means to recover sufficient quantities of groundwater is not available, or
w here dilution with contaminated groundwater might diminish the effectiveness of the
discharge.
•
If the discharge has the potential to generate hazardous or explosive levels of vapors or
gases in the vicinity of vulnerable receptors, vapor recovery methods should be
employed . In such cases, it may sometimes be sufficient to have a vapor recovery
system on standby as a contingency with proper monitoring . The operation of a vapor
recovery system does not in any way preclude the need for proper monitoring to ensure
protection from vapor hazards.
•
In circumstances where the discharge is likely to result in exacerbation, or where
receptors are immediately threatened and other plume control mechan isms are not
sufficient or otherwise unreliable, groundwater capture methods may be warranted. In
some cases, it may be sufficient and appropriate to have a capture system on standby
as a contingency.
MONITORING REQUIREMENTS
Proper monitoring is critical to a successful in situ remed iation , yet is one of the most common
shortfalls when implementing an in situ remediation. This is usually because the monitoring
program is overly simplistic and assumptive, which leads to data gaps in some areas of
evaluation, while attaining superfluous amounts of data in other areas. In situ remed iation
generally warrants monitoring of multiple environmental media and monitoring parameters to
ensure implementation in a safe and effective manner. Periodic monitoring of contaminants of
concern alone is not sufficient in this regard because it often provides virtually no information as
to health, safety, or environmental concerns associated with the discharge, and provides only
cursory evidence as to w hether or not a remedy is effective. That is not to say that monitoring
programs have to be extremely complex, but rather that strategic thinking in the development of
a monitoring program is likely to lead to better data that is gathered more efficiently, ultimately
leading to a more informed evaluation and a more cost effective in situ remediation project.
Monitoring requirements for in situ remediation are very application-specific. As such, a
comprehensive description of the monitoring requirements and protocol for in situ remediation is
beyond the scope of this document. However, general considerations for developing or
evaluating the environmental media to monitor and common monitoring parameters for in situ
remediation are described below . It is ultimately up to the party implementing the discharge to
develop a thorough monitoring plan. In developing a monitoring plan, the party implementing
the discharge should consult reliable scientific, engineering, and technical references specific to
the remed ial option to determine what med ia and parameters warrant mon itoring.
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7.1 Purpose and Objectives
Every monitoring plan for in situ remediation should be designed with application-specific
purposes and objectives in mind and at a minimum should address the following areas:
7.1.1 Assuring Protection of Public Health. Safety. and Environment
The monitoring plan must ensure timely protection of public health, safety or welfare, and any
environmental receptors that have the potential to become affected as the result of the
discharge . For receptors that may already be affected, the mon itoring plan should be sufficient
to identify (in a timely manner) whether the discharge may result in an increased threat to that
receptor. For example, if contamination is already discharging to a surface water body at
unacceptable concentrations, the remedial discharge must not result in any increased
contaminant loading to that receptor. The monitoring plan must also ensure that the remedial
discharge is not resulting in any contaminant exacerbation or otherwise any appreciable
increase in the extent of contamination . Further, the monitoring plan must set action levels that
would trigger specific response actions.
7.1.2 Evaluating Remedial Integrity and Effectiveness
The monitoring plan should provide for sufficient means to qualify and quantify the effectiveness
of the remedial discharge in achieving remedial objectives, including consideration of facilityspecific variables such as periodic fluctuations in contaminant concentrations, to distinguish
w hether genuine reductions in contaminant concentrations are occurring. Potential "side
effects" from the remedial discharge should also be considered in the monitoring plan as part of
the evaluation of integrity of the remedy. For example, if a remed ial discharge has the potential
to leach metals from soil, the monitoring plan should be sufficient to show w hether this is
occurring , and if so, whether metal concentrations will sufficiently attenuate before reaching a
receptor. The mon itoring plan should also include specified parameters and time frames that
define the success or failure of the remedy. Again, it should be noted that samples collected
directly from treatment wells are generally not representative of the treatment area as a whole,
and should not be used for evaluating (or demonstrating) remed ial integrity and effectiveness.
7.1.3 Assuring that Action Levels are not Exceeded at Compliance Monitoring
Points
The monitoring plan must ensure that the extent of contamination remains defined and that
contaminants do not exceed applicable criteria at other specified compliance monitoring points
(e.g., in sentinel monitoring wells).
7.2 Monitoring Phases
Monitoring phases can generally be broken down into the following: Baseline, coimplementation, post-implementation or remedial evaluation, and compliance.
7.2.1 Baseline Monitoring
Baseline sampling and analysis serves multiple purposes and should be completed prior to
initiation of any in situ remedial discharge or series of in situ remedial discharges. Baseline
sampling of geochemical, biochemical, and/or biological parameters should be completed , as
applicable, as part of the in situ remedial evaluation, selection, and design process. This
sampling also serves as a basis for gauging certain effects from remedial processes.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Michigan Department of Environmental Quality
Establishing baseline concentrations for contaminants of concern and potential daughter
products is necessary for evaluating initial risks to environmental receptors, and also for
gauging remedial success.
Four (4) consecutive quarters of sampling are preferred for establishing contaminant baseline
concentrations, as this allows for a means to roughly gauge seasonal fluctuations in
contaminant concentrations; however, less extensive baseline monitoring may be appropriate in
some circumstances. In addition, it may sometimes be necessary to establish baseline
concentrations for other parameters that may be present in both the treated media and in the
remedial discharge to allow a determination of what component(s) may be due to the discharge
versus naturally occurring or pre-remedial conditions.
7.2.2 Co-implementation Monitoring
Co-implementation monitoring refers to any monitoring conducted as part of the in situ remed ial
discharge protocol , or otherwise just prior to, during, or immediately after implementation of an
in situ remedial discharge. This monitoring generally centers around the assessment of the
immediate environmental or health and safety concerns posed by an in situ remedial discharge
or the general progress of the discharge. It generally comprises field screening techniques to
assess immediate effects, such as groundwater mounding, temperature changes, vapor and
explosion hazards, certain geochemical changes (e.g. , dissolved oxygen, pH , oxidationreduction potential (ORP). Co-implementation mon itoring must be sufficient to monitor the
general progress and immed iate effects of the discharge.
7.2.3 Post-implementation or Remedial Evaluation Monitoring
Post-implementation monitoring refers to any monitoring follow ing the implementation of an in
situ remedial discharge that is conducted specifically for the purposes of evaluating the
effectiveness and integrity of the remedy. Post-implementation monitoring must include
assessment of:
•
•
•
•
Any potential "lingering" effects from the in situ remed ial discharge;
Changes to geochemical, biochemical , or biological conditions (both desirable and
undesirable);
Rates of contaminant degradation following in s;tu remedial discharges; and
Other factors as necessary to evaluate the integrity of the remedy.
7.2.4 Compliance Monitoring
Although compliance monitoring may often be completed in the same event and may also use
some of the same samples and analytical data as attained for post-implementation or remedial
evaluation monitoring, it is distinguished here because it serves a different purpose, does not
always require the same parameters, and does not necessarily warrant the same sampling
frequency as the latter. For example, some technologies warrant a high frequency of remedial
evaluation sampling in the treatment area (e.g., perhaps sampling at 1, 7, 14, 30, 60, and 180
days following each discharge event), and may also warrant a comprehensive list of analytical
parameters (e.g ., geochemical, biochemical , biological, contaminants of concern, and daughter
product parameters). By comparison, compliance monitoring may take place well outside of the
treatment area (although not always); generally warrants a much less substantial sampling
frequency (e.g., quarterly or biannually); and may, depending on facility-specific circumstances,
RRD Operational Memorandum No. 4 ,
Attachment 9, In Situ Remedial Discharges
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Remediation and
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Michigan Department of Environmental Quality
warrant a less comprehensive list of parameters (e.g ., contaminants of concern, daughter
products, and select geochemical or biochemical parameters based on remedial evaluation
monitoring). The differences between remedial evaluation and compliance monitoring are
mentioned here to point out the fact that overly simplified monitoring plans may not be sufficient
or cost effective in implementation .
7.3
Environmental Media and Common Monitoring Parameters
The following lists the common environmental media and parameters that are generally
monitored as part of an in situ remediation. The applicability of these items varies depending on
the selected remed ial option and facility-specific circumstances.
7.3.1 Soil Gas
Soil gas should be monitored before, during, and after implementation of an in situ remedial
discharge when the contaminants of concern or remedial reagents have the potential to lead to
vapor or explosion hazards. This includes circumstances where a remedial discharge has the
potential to generate, mobilize, or displace vapors or generate higher than normal
concentrations of oxygen gas, and these vapors or gases have the potential to migrate into
enclosed spaces. In some circumstances, field screening techniques (e.g., photoionization or
gas detectors) may be sufficient to assess risks, although some circumstances warrant the
collection of soil gas samples for lab analysis. Soil gas monitoring is generally conducted for
the purposes of sentinel monitoring to protect specific receptors; therefore, action levels should
be specified for soil gas monitoring that will trigger specified response actions necessary to
protect receptors. In some circumstances, it may be beneficial or even necessary to mon itor
various soil gas parameters for purposes other than vapor or explosion hazards, such as
remedial evaluation . The RRD Operational Memorandum No. 4, Attachment 4 (and
Attachment 5 if methane is a concern) should be consulted for guidance on soil gas monitoring.
7.3.2 Indoor Air and Enclosed Spaces
Indoor air mon itoring (including monitoring of enclosed spaces such as storm sewers, utility
man-ways, etc. ) should be included in the monitoring program for any facility where vapor or
explosion hazards are a concern. However. when assessing any circumstance w here acute
risks (including explosion hazards) have the potential to develop rapidly upon implementation of
a discharge. this type of monitoring cannot be exclusively relied upon to protect public health
and safety. For contaminants w ith potential chronic impacts, indoor air sampling should be
implemented in conjunction with a more reliable monitoring method, or as a contingency that is
implemented when a more reliable method indicates the exceedence of specified action levels.
For example, it is often more appropriate to use soil gas monitoring as the primary basis for
assessing potential risks to indoor air (i.e., sentinel monitoring), with indoor air monitoring
implemented as a contingency only after specified action levels set for soil gas monitoring are
exceeded . For contaminants that may pose an explosion hazard, indoor air sampling could
provide an additional safeguard, but earlier detection at sentinel monitoring points still would be
necessary. The RRD Operational Memorandum No. 4, Attachment 4 (and Attachment 5 if
methane is a concern) should be consulted for gu idance on indoor air and enclosed space
monitoring.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Remediation and
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Michigan Department of Environmental Quality
7.3.3 Ambient Air
Ambient air monitoring is warranted whenever a discharge has a reasonable potential to
generate concentrations of vapors in ambient air that either present unacceptable inhalation
exposures to workers or non-workers, or that could present a risk of fire or explosion. In most
applications, in situ discharges are applied at some depth beneath a cover material (i.e., soil
and/or pavement), which usually inhibits the rapid diffusion of vapors to the surface, thereby
minimizing the ability of gases or vapors to accumulate at hazardous concentrations in ambient
air. However, this alone does not necessarily preclude the need for ambient air monitoring .
In determining whether ambient air monitoring is necessary as part of an in situ remedial
strategy, the following should be considered:
•
•
•
•
•
•
•
The concentrations of contaminants in soil or groundwater, especially where grossly
contaminated med ia is present;
The concentrations at which contaminants of concern or remedial constituents become
toxic in air, especially if toxic at very low concentrations;
The potential for explosive conditions to develop, in light of the chemical properties of
the contaminants of concern and potential by-products from the discharge (e.g.,
generation of oxygen gas);
The proximity of the treated media to the surface;
The properties of the soil and/or cover above the treated media;
Whether engineering controls are implemented as part of the remedial process, such as
soil vapor extraction , that will otherwise stop the migration of gases or vapors to the
surface; and
The presence of conduits to the surface for gases and vapors, such as monitoring or
treatment wells, that can result in the impact to the breathing zone air.
Examples of where ambient air monitoring may be required as part of an in situ remedial
strategy include the application of oxidants to open excavations as a means to treat petroleum
or solvent contamination ; or discharges through, or in the vicinity of open wells w here off-gasing
through the well has the potential to result in unacceptable breathing zone exposures to site
workers.
7.3.4 Groundwater
Groundwater monitoring is warranted at nearly every site in Michigan when implementing an
in situ remediation to evaluate contaminants of concern, daughter products, geochemical
parameters, biochemical parameters, and/or biological parameters, as appropriate to the
application. In circumstances where vapor or explosion hazards are of concern , and the
remedial discharge involves slow reaction rates (such as is generally expected with in situ
bioremediation), it may sometimes be appropriate to rely on groundwater samples as tools for
assessing potential vapor or explosion risks.
For this type of assessment, Part 201 Criteria Application Guidesheets 4 and 5 (developed
under R 299.5714) and Guidesheets 8 and 9 (developed under R 299.5706a(1)) should be
consulted as appropriate.
If the groundwater surface water interface (GSI ) pathway is relevant for a facility, sampling the
groundwater prior to its discharge to a surface water or storm sewer is necessary as part of
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Remediation and
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Michigan Department of Environmental Quality
assessing the risks posed by the in situ remedial discharge. However, in some circumstances,
it may be necessary to supplement GSI groundwater monitoring with direct sampling of the
receiving water body or storm sewer.
Some remedial constituents, such as hydrogen peroxide, ozone, or permanganate, can be
acutely toxic to aquatic life at very low concentrations; therefore, a similar assessment may also
be warranted for remedial constituents. However, as in the assessment of indoor air hazards, if
any potential impact to GSI receptors is anticipated , it is never appropriate to assess this
exposure pathway via surface water or storm water sampling exclusively. Rather, GSI
compliance mon itoring wells and sentinel wells where appropriate must serve as the primary
means to assess threats to GSI receptors.
7.3.5 Soil
In addition to assessing soil contaminant concentrations as part of the overall site
characterization, periodic monitoring of vadose or saturated zone soil contamination may be
necessary in some circumstances in order to evaluate the efficacy of an in situ remed ial
strategy. This should be included in the monitoring plan for any in situ remedial strategy that is
specifically intended to remediate soil contamination . Such monitoring may also be warranted
in circumstances w here soil contamination presents an ongoing impact to groundwater
contamination, or where the remedial reagents and processes themselves have the potential to
contribute to soil contamination .
For in situ remedial technologies that are dependent on or inhibited by certain geochemical
conditions (naturally occurring or anthropogenic), baseline soil sampling is usually required .
Although this does not generally warrant ongoing monitoring, there may be circumstances
w here periodic mon itoring for such parameters is appropriate.
7.4
Common Monitoring Parameters
The following briefly describes some of the common monitoring parameters associated with
various in situ remed iation technologies. Please be advised that this discussion is neither
comprehensive nor intended to be so. Additional parameters may be warranted depending on
facility-specific circumstances.
7.4.1 Contaminants of Concern and Daughter Products
Contaminants of concern or contaminant indicator parameters and their respective daughter
product concentrations should be characterized as part of the baseline, co-implementation,
remedial evaluation, and compliance mon itoring, and is relevant for all types of environmental
media as deemed necessary for the application. For the purposes of remedial evaluation, the
level and frequency of monitoring should be sufficient to quantify degradation rates and/or to
assess remedial progress in light of specified remedial objectives. Further, assessment of
potential daughter products should show w hether daughter products are being generated, and if
so, whether daughter products are sufficiently abated . For the purposes of compliance
monitoring, parameters should be sufficient to show that the extent of the contaminants of
concern and daughter products remains delineated and that action levels are not exceeded in
the compliance monitoring points.
RRD Operational Memorandum No. 4 ,
Attachment 9, In Situ Remedial Discharges
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Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
7.4.2 Geochemical and Biochemical Parameters
The parameters used for geochemical and biochemical characterization are similar with
consideration depending on whether the remedy is chemically or biologically oriented . Such
parameters either inhibiUinterfere w ith or enhance chemical reactions in chemically based
technologies (such as in s;tu chemical oxidation), or may be necessary for or detrimental to the
establishment or growth of the specific types of microbes necessary for intended bioremediation
processes. Similarly, some of these parameters may be more indicative of chemical or
biological processes than they are necessary for these processes to occur. Further, some
geochemical and biochemical parameters have the potential to become contaminants of
concern due to chemical changes brought about by remedial processes, such as the alteration
of metals to a more mobile valent state, or conversions between ammon ia and nitrate .
Characterization of geochemical and biochemical parameters is generally applicable to
groundwater and soil, although other media may warrant characterization (e.g ., oxygen, carbon
dioxide, or methane in soil gas). Common geochemical and biochemical parameters for soil
include: metals, fraction of organ ic carbon, natural oxidant demand (uncontaminated soil
matrix), and soil oxidant demand (contaminated soil matrix). Common parameters for
groundwater include: dissolved oxygen, dissolved carbon dioxide, dissolved methane, total
metals, nitrate, sulfate, sulfide natural oxidant demand (or chemical or biological oxidant
demand, as appropriate), specific conductance, alkalinity, total organic carbon, volatile fatty
acids, pH , and ORP.
7.4.3 Biological Parameters
Characterization of biological constituents is necessary if a remedial technology relies on the
enhancement of biological processes or bioaugmentation to degrade contamination. This type
of monitoring should be included as part of the baseline and remedial evaluation mon itoring and
is applicable to soil or groundwater media. In some circumstances, analysis of total
heterotrophs as an ind icator of relative microbial abundance (pre- and post-remedial discharge)
may be sufficient to confirm that conditions are amenable to microbe survival , growth, and
reproduction .
However, for remedies that rely on the presence of specific species, a more specific analysis
may be warranted to confirm that the right organisms are present. In situ reductive
dechlorination of dissolved-phase chlorinated hydrocarbons is the most commonly encountered
example of enhanced bioremediation or bioaugmentation where a species-specific analysis is
warranted. This remedial technology relies heavily on co-metabolic processes brought about by
the presence of specific species of bacteria (i.e., dehalococcoides ethenogenes) to degrade
chlorinated hydrocarbon contamination. Further, there are specific genotypes requ ired to
produce the necessary enzymes (vinyl chloride reductase) for the complete degradation of
contamination. As such , implementation of this technology may require a species-specific
analysis, and/or analysis for the vinyl chloride reductase gene (unless it can be demonstrated
that vinyl chloride will breakdown into ethane via another mechanism).
7.4.4 Physical Parameters
Various physical parameters, such as temperature, water levels/hydraulic grad ients, pressure,
vacuum, hydraulic conductivity, or even color may be necessary as part of the coimplementation monitoring to assess the progress of or effects from remedial discharges.
RRD Operational Memorandum No. 4 ,
Attachment 9, In Situ Remedial Discharges
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Remediation and
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Michigan Department of Environmental Quality
Often, such monitoring is necessary to ensure the protection of public health and safety and
certain environmental receptors during implementation of a remedial discharge.
7.4.5 Discharge Constituents
Monitoring of in situ remedial discharge constituents (or add itives) is necessary if the constituent
in the in situ remedial discharge (or a by-product of a discharge constituent) has the potential to
accumulate in the environment at concentrations exceeding residential cleanup criteria, or if the
constituent otherwise has the potential to cause a threat to public health, safety, or the
environment. Be advised that there are many remedial constituents in the latter category for
w hich there are no criteria developed . These include oxidants (ozone, hydrogen peroxide,
permanganate) which can be acutely toxic to aquatic life at relatively low concentrations. This
can also include any unconsumed organic matter added as a food source to support microbial
growth. In most cases, co-implementation and remedial evaluation monitoring of discharge
constituents is beneficial or necessary in establishing distances or radii of influence from
remedial discharges, or ensuring complete consumption or breakdown of certain remedial
constituents.
8.0
APPLICABILITY OF AND COMPLIANCE WITH THE PART 22 RULES
Authorization for all in situ remedial discharges falls under the Part 22 Rules. In summary, there
are two (2) primary mechanisms by which the Part 22 Rules authorize in situ remedial
discharges. The first option is to obtain a discharge permit through the MDEQ Water Bureau.
The second option is to obtain a permit exemption pursuant to R 323 .221 O(u)(ii) and (iii ). The
limited resources of the MDEQ do not allow the investment of staff resources to review a
proposal for a permit that would otherwise qualify for an exemption. Permit exemptions
authorized under R 323.221 O(u)(ii ) have essentially the same requirements as authorization
under R 323.2210(u)(iii), only that the former does not require prior approval by the RRD .
Further information on the applicability of the Part 22 Rules to an in situ remediation and the
general requirements for obtaining a permit exemption are described in Appendix A.
Any direct or indirect discharge of a material (liquid, solid, or gas) into groundwater or onto the
ground for the purposes of an in situ remediation must be authorized by a groundwater
discharge permit or an appropriate permit exemption under the Part 22 Rules. For most types
of in situ remedial discharges, prior approval of a remedial investigation, feasibility study (or
associated pilot study), or remediation plan from the RRD will be required before the discharge
can be lawfully implemented.
9.0
DOCUMENTATION REQUIREMENTS FOR OBTAINING A PERMIT
EXEMPTION
A permit exemption for remedial investigations, feasibility or pilot studies, or remedial action
discharges (direct or indirect) that exceed or are anticipated to exceed generic residential
cleanup criteria (and are subject to authorization under R 323.221 O(u)(iii)), can be obtained by
virtue of prior RRD approval of an associated remediation investigation, feasibility study, or
remediation plan .
For discharges implemented as part of a FAR or RAP, R 323.2210(u)(iii ) provides for a permit
exemption with approval from the RRD of the FAR or RAP. The Part 22 Rules do not provide
for a permit exemption w ith the RRD approval of only portions of a FAR or RAP; therefore, all of
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Michigan Department of Environmental Quality
the information required for a complete FAR or RAP must be provided, even if portions of the
required information are not directly related to the proposed in situ discharge.
For discharges implemented in the context of a remediation investigation or pilot study subject
to approval pursuant to R 323.221 O(u)(iii ), the proposed discharge must be documented to the
extent necessary to allow the RRD to evaluate the basis for and objectives of the discharge, the
design and operational parameters, and how the discharge will be monitored and evaluated.
This documentation is necessary in order for the RRD to make a determination as to whether or
not to approve of the discharge in the context of an approved remediation investigation or
feasibility study.
In order to obtain a permit exemption for a remedial investigation , pilot study, or remed iation
plan discharge pursuant toR 323.2210(u)(iii), documentation must be submitted to the RRD that
describes all of the following:
•
Objectives of the discharge;
•
Site characterization information, including: (1) The nature and extent of contamination,
(2) Geological and hydrogeological conditions, (3) Geochemical, biogeochemical, and/or
biological characterization, and (4) Exposure pathways, transport mechanisms, and
potential receptors;
•
The remedial strategy and technical basis for selection of the in situ remedial technology
and/or remed ial strategy in light of facility-specific conditions;
•
How the in situ remedial strategy will be implemented in a manner that is protective of
the public health, safety, and welfare, and the environment. This should include an
evaluation of specific concerns that may be encountered during the discharge (e.g.,
vapor migration, explosion hazards, formation of hazardous daughter products,
exacerbation of contamination , etc.) and a description of how each environmental
receptor will be protected ;
•
Design and construction plans, including: discharge or injection points, comprehensive
list of constituents to be discharged , flow rates, discharge volumes, discharge protocol ,
and other pertinent information ;
•
A detailed monitoring plan, including parameters, general implementation schedule, data
presentation and evaluation plan; and
•
Contingency planning, including specified action levels that will trigger contingent
response actions and time frames for implementing them.
In deciding what specific information to submit, R 299.5532 (RAP requirements) or
Section 21309a of NREPA (corrective action plan requirements) should be consulted in addition
to published references specific to the in situ remedial application. Even where an in situ
remedial discharge is proposed as part of a remedial investigation or pilot study, and therefore
does not necessarily have to meet all of the RAP or FAR requirements, these requirements still
provide a good reference for evaluating what specific information and documentation must be
submitted in order to obtain the RRD approval.
RRD Operational Memorandum No. 4 ,
Attachment 9, In Situ Remedial Discharges
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Michigan Department of Environmental Quality
10.0 MISCELLANEOUS RECOMMENDATIONS FOR DOCUMENTATION
If a pilot study is required in order to determine what the essential or critical elements of a
remedial strategy will be (e.g. , such as to determine what remedial option to proceed with), it is
recommended (and in many circumstances required) that the investigation be completed
separate from and prior to the final development of the FAR or RAP, and the results from the
investigation incorporated therein. If the purpose is to establish design parameters rather than
to select a remedial option, it is generally acceptable to incorporate the pilot study into the FAR
or RAP implementation . If the purpose of the pilot study is to decide w hether or not to amend a
FAR submitted under Part 213, it is acceptable to rely on the existing FAR in the interim if it is
otherwise complete.
Plans for remedial discharges should incorporate some degree of flexibility to allow for
adjustments during implementation. As such, w here parameters are expected to vary
throughout the process, such as discharge rates, concentrations or volumes, or geochemical or
biochemical parameters, it is recommended that parameter ranges be specified , where
appropriate, rather than specific values.
Often the most efficient manner to present a monitoring plan is in a table format that specifies
monitoring parameters, monitoring location, media to be monitored, and time frames.
11.0 SUBMITTALS REQUIRING PRIOR RRD APPROVAL
The FARs, RAPs, and plans for pilot studies or interim responses that require prior RRD
approval in order to attain a permit exemption for a remedial discharge should be submitted
directly to the respective MDEQ district office, and may be addressed directly to the MDEQ
project manager assigned to the site (this does not represent any change in procedure). Except
for proposals provided as part of a FAR, submittals should include a brief cover letter indicating
that the RRD approval of the plan is requested in order to attain a permit exemption for a
remedial discharge. The standard FAR cover sheet has been modified with a check box to
indicate that the RRD review is required.
In order to prevent excessive delays in the implementation of corrective actions, submittals that
requ ire prior approval in order to attain a permit exemption are given priority by the RRD.
Although the RRD will try to respond to these submittals as qu ickly as possible, the turnaround
time for the RRD review is dependent on workload as well as the complexity of the review .
Persons seeking approval from the RRD of a plan are advised to notify the RRD project
manager of the upcoming submittal ahead of time in order to facilitate a more expedient review .
The RRD will respond to the FAR, RAP, and feasibility or pilot study submittals that propose an
in situ remedial discharge in writing to the person or institution that is responsible for
undertaking the response actions to address the release (generally the "owner" and/or
"operator" as defined in Parts 201 and 213), or who is voluntarily undertaking the response
actions under Parts 201 or 213. Written notification from the RRD stating that the FAR, RAP, or
feasibility study submittal is approved provides the requisite authorization pursuant to
R 323.221 O(u)(iii ) of the Part 22 Rules to proceed with implementation of the remedial
discharge . Note that if a submittal omits required information or is otherwise substantially
deficient, the RRD project manager may request revisions prior to conducting a formal review
and written response .
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Michigan Department of Environmental Quality
This Operational Memorandum is intended to provide guidance to foster consistent application
of Part 201 and Part 213 of NREPA and the associated Administrative Rules. This document is
not intended to convey any rights to any person nor itself create any duties or responsibilities
under law . This document and subject matters addressed herein are subject to revision.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Michigan Department of Environmental Quality
12.0 REFERENCES
Federal Remediation Technologies Roundtable. Publications Link:
http://www.frtr.gov/publib.htm and http://frtr.gov/pdf/epa542r0301 1.pdf.
Huling, S.G., and Pivets, B.E., "In situ Chemical Oxidation," U.S. EPA Engineering Issue,
EPA-600-R-06-072. U.S. EPA Office of Research and Development, National Risk
Management Research Laboratory. August 2006.
Industrial Wastewater Reference Library Peroxide Applications. Fenton's Reagent: IronCatalyzed Hydrogen Peroxide.
(www.h2o2.com/applications/industrialwastewater/fentonsreagent.html).
Interstate Technology and Regulatory Council, In situ Chemical Oxidation Team, 2005.
Technical and Regulatory Guidance for In situ Chemical Oxidation of Contaminated Soil
and Groundwater.
Leethem, J.T., In Situ Chemical Oxidation of MTBE: A Case Study of the Successful
Remed iation of a Large Gasoline Release. Contaminated Soil Sediment and Water
July/August 2002, pages 70-75.
Newell, C.J., Winters, J.A. , Miller, R.N. , Gonzales, J., Riifai, H.S., and Wiedemeier, T.H.,
Modeling Intrinsic Remediation with Multiple Electron Acceptors: Results from Seven
Sites. Presented at Petroleum Hydrocarbons and Organic Chemicals in Ground Water
Conference, Houston, TX (November 29, 1995).
Palmer, P., Hall, S., and Darby, J., The Future of Petroleum Hydrocarbon Remed iation : Site
Closure through Enhancement of In situ Biological Degradation. ARCAD IS G&M, Inc.
U.S. EPA, 2004. "How to Evaluate Alternative Technologies for Underground Storage Tank
Sites: A Guide for Corrective Action Plan Reviewers," EPA-51 0-R-04-002, Solid Waste
and Emergency Response 5401 G, May 2004. (www.epa.gov/oust/pubs/tums.htm).
U.S. EPA, 2000. Ray, A.B ., and Selvakumer, A. , 'Treatment of MTBE Using Fenton's
Reagent," EPA-600-JA-00-193.
U.S. EPA, 1998. "Field Applications of In situ Remediation Technologies: Chemical Oxidation,"
EPA-542-R-98-008, Solid Waste and Emergency Response 5102G, September 1998.
(www.epa.gov/swertio1).
U.S. EPA, 2000. "Engineered Approaches to In situ Bioremediation of Chlorinated Solvents:
Fundamentals and Field Applications" (Revised July 2000).
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
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Remediation and
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Michigan Department of Environmental Quality
APPENDIX A
Discharge to a Plume of Contamination Without a Permit
(Part 22 Rules, promulgated pursuant to Part 31 of NREPA)
Section 3112(1) of Part 31 1 of NREPA states that, "A person shall not discharge any waste or
waste effluent into the waters of this state unless the person is in possession of a valid permit
from the department. .." Section 3109 of NREPA states that, "A person shall not directly or
indirectly discharge into the waters of the state a substance that is or may become injurious to
any of the following ... " This section goes on to list public health, safety, or welfare, domestic,
agricultural , recreational, etc., as the protected uses of the waters of the state . This is reiterated
in R 323.2204 of the Part 22 2 Rules.
The Part 22 Rules establishes the criteria under which a discharge 3 (e.g., in situ remedial
treatment) to groundwater meets the Section 3109 requirement of preventing the discharge of a
substance that is or may become injurious to the protected uses. The Part 22 Rules also
establishes the criteria for obtaining valid authorization from the MDEQ, in accordance with
Section 3112(1), for the discharge of a waste or waste effluent into the waters of this state . The
Part 22 Rules are applicable to the discharge and any effects resulting from the discharge;
however, they do not control the level of remediation that must take place relative to the plume
of contaminated groundwater.
Pursuant to the Part 22 Rules, the discharge of any pollutant4 , waste 5 , wastewater6 , or waste
effluent to groundwater constitutes a discharge of a waste or waste effluent as described in
Section 3112; therefore, all discharges related to the groundwater cleanup activities requires a
groundwater discharge authorization. The Part 22 Rules provides for the following types of
authorizations: A permit exemption (R 323.221 0), permit by rule (R 323.2211 and R 323.2213),
general permit (R 323.2215), or specific discharge permit (R 323 .2216 and R 323.2218).
1
Part 31, Water Resources Protection , of the Natural Resources and Environmental Protection Act,
1994 PA 451 , as amended (NREPA).
2
Part 22 Rules, Groundwater Quality Administrative Rules, promulgated pursuant to Part 31, Water
Resources Protection, of NREPA.
3
"Discharge" means any direct or indirect discharge of any of the following into the groundwater or onto
the ground: (i) waste, (ii) waste effluent, (iii) wastew ater, (iv) pollutant, (v) cooling water, (vi) a
combination of items (i) to (v) {R 323.2201 (i)}.
4
"Pollutant" means any substance that may adversely affect a protected use of w aters of the state,
~R 323.2202(m)}.
"Waste" means any waste, w astew ater, waste effluent, or pollutant that is discharged into water
~R 323.2203(n)}.
"Wastew ater" means liquid w aste discharged directly or indirectly into the w aters of the state or onto the
ground that results from industrial or commercial processes or municipal operations, including liquid or
w ater-carried process w aste, cooling or condensing waters, and sanitary sew age. {R 323.2203(o)}.
The w astewater associated with environmental response activity referenced in R 323.2210(u) was
primarily intended to address discharges from groundwater purge and treatment. The discharges
associated with in situ remedial discharges similarly meet the w astew ater definition.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
31 of 34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
Of these authorizations, R 323.221 O(u) provides an exemption that allows wastewater
associated w ith an environmental response activity, under certain constraints, to be discharged
to the plume of groundwater contamination, including an area 100 feet hydraulically upgradient
of the leading edge of the plume, without a permit. Note that it is very important that those
responsible for managing and implementing a discharge (e.g., environmental consultants, liable
parties, parties voluntarily undertaking response activities, state project managers, and others)
carefully consider the conditions under which a R 323.221 O(u) exemption applies.
R 323.221 O(u) contains three (3) different provisions that apply to discharges associated with
environmental response activities, depending on the nature of the discharge. Two (2) of these
provisions apply to in situ remedial discharges (e.g., remedies that involve the use of hydrogen
or oxygen releasing agents, oxidants, nutrients, microbes, permeable reactive barriers, etc.)
w hich include the following:
(ii) A remed ial investigation, feasibility study, or remed ial action discharge that is at or below
the residential criteria;
(iii) A discharge for a remedial investigation , feasibility study, or remedial action above the
residential criteria, if a remediation investigation, feasibility study, or remediation plan
has been approved by the department division that has compliance oversight. The
remediation plan shall indicate that the treatment system is designed and will be
operated so that contaminated groundwater will eventually meet the appropriate land
use based cleanup criteria authorized by Section 20120a(1)(a) of the act, if applicable,
or Section 21304(a) of the act, if applicable.
Note that the definition of a "discharge" [see R 323.2201 (i)] includes any direct or indirect
discharges; therefore, the determination of which of the above applies must consider the
content of the discharged material(s), including any additives contained therein, in addition to all
potential secondary effects that may result from the discharge. Also, note that the definition of a
discharge is not limited to discharges of liquid materials, but rather, also applies to discharges of
solids and gases.
If the discharge is proposed for a remedial investigation, feasibility study (or pilot study),
remedial action, or corrective action, a determination must be made whether the discharge
contains or creates any substances that are above residential criteria authorized by
Section 20120a(1)(a) or Section 21304(a) of NREPA, as applicable. Pursuant to
R 323.2206(1), it is the responsibility of the person proposing a discharge to provide the
information as required or necessary for the MDEQ to make a decision (or to concur) as to
w hether a discharge may contain or create substances above residential criteria. In some
circumstances, this effort may warrant some level of site-specific testing or analysis.
If the discharge is below criteria, then the discharge is exempt from the requirement to obtain a
permit. If a discharge has a reasonable potential to cause an indirect discharge that may
exceed residential criteria, even if the content of the discharged material(s) in and of itself does
not exceed residential criteria, then the discharge is subject to division approval pursuant to
R 323.221 O(u)(iii ) before the discharge can be lawfully implemented, unless it is otherwise
demonstrated (to the satisfaction of the RRD) that authorization under R 323.221 O(u)(ii ) applies
instead.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
32 of 34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
If any substance in the discharge is above residential criteria or may cause a discharge above
residential criteria, the person proposing the discharge must demonstrate that a feasibility study,
RAP, or FAR has been approved by the RRD as the division that has compliance oversight.
This demonstration must consist of documentation to the file by the appropriate RRD
representative that the conditions of R 323 .2210(u)(iii) have been met.
Generally, the RRD considers R 323.221 O(u)(iii ) applicable whenever the discharge may result
in the following conditions:
•
•
•
Alteration of the geochemical equilibrium in the subsurface in a manner that promotes
leaching of metals;
Formation/creation of reactive, hazardous, or otherwise non-inert by-products, including
hazardous "daughter" products formed from the breakdown of the originally released
material(s); or
Exacerbation of existing contamination .
For example, the discharge of hydrogen peroxide is a relatively common method proposed for
treating petroleum contamination in situ. Although residential criteria have not been developed
for hydrogen peroxide, injection of this acidic and oxidative material has been shown to cause
metals to leach from soil into the groundwater. Similarly, supplementation of an aquifer with
microbes, nutrients, and/or a food source to promote bioremed iation can also alter groundwater
geochemical conditions such that metals leach into the groundwater. Therefore, either of these
types of remedies requ ires approval pursuant to R 323.221 O(u)(iii ).
Remed ial discharges that involve oxidative or enhanced biological processes (including pilot
studies) are subject to division approval pursuant toR 323.2210(u)(iii). This includes (but is not
limited to): hydrogen peroxide (including Fenton's Reagent or any "modified" Fenton's
Reagent), permanganates, persulfates, ozone, reductive dehalogenation , or other enhanced
bioremediation . Be advised that this is not all inclusive and that other types of in situ remed ies
not identified herein may also be subject to division approval. Please contact the RRD project
manager if there are any questions pertaining to the applicability of R 323.221 O(u)(iii) to a
particular in situ remedy.
For in situ remedial discharges of oxygen or ambient air to groundwater (i.e. , oxygen or air
sparging), the MDEQ has determined that these discharges, when specifically used to treat
hydrocarbon contamination, are authorized under R 323 .2210(u)(ii) and do not typically require
prior approval by the RRD. The basis for this determination is that in most applications it is not
expected that the operation of an oxygen or air sparge system would create a direct or indirect
discharge above residential criteria. This determination is based on the condition that there are
no contaminants in the oxygen or air, including contaminants such as compressor oils, and that
the system is operated in a manner that will not exacerbate contamination . However, although
these discharges do not typically requ ire prior division authorization, this should in no way be
construed to waive any obligations to comply with other requirements under the Part 22 Rules,
Part 201 , and/or Part 213 (as applicable). Note that Section 21309a has very specific
requirements regarding the implementation of corrective actions. This information must be
submitted prior to implementing any in situ remedy, unless the remedial discharge is specifically
intended to meet initial response obligations under Section 21307.
RRD Operational Memorandum No. 4,
Attachment 9, In Situ Remedial Discharges
33 of 34
Interim Final
December 2008
IDE€\1
Remediation and
Redevelopment Division
Michigan Department of Environmental Quality
Other Permit Exemption Requirements
Discharges are exempt from permitting if they meet the criteria listed in R 323.221 O(u),
but they are never exempt from the requirements of Section 3109 of NREPA or
R 323.2204. Further, regardless of whether an in situ discharge qualifies as an "item that is
permitted to be discharged without a permit" under R 323.2210(u)(ii) or (iii ), the discharge must
comply with all other provisions of the Part 22 Rules, Part 201 , and/or Part 213 (as applicable).
For example, the person or persons completing the discharge remains responsible for taking the
precautions to ensure that the discharge does not result in unacceptable exposures (such as
could occur if the sparge system results in increased volatilization and/or vapor migration), does
not exacerbate contamination (such as could occur if a sparge system was operated in an area
of free product or heavily contaminated groundwater without hydraulic controls), or does not
otherwise create fire, explosion, or vapor hazards. Further, "the discharge shall not be, or not
be likely to become, injurious [R 323.2204(a)]," and "shall not cause nuisance cond itions
[R 323.2204(a)]."
R 323.221 O(u) requires compliance with R 323.2204, which states that a person cannot
discharge anything that is or may become injurious to the protected uses of the waters of the
state. For discharges associated with groundwater remediation , any additive contained in the
discharge, or any secondary effect that occurs as a result of the discharge, must meet
the groundwater standards described in R 323.2222. For example, if potassium
permanganate is used as a chemical oxidant to destroy chlorinated compounds, the residual
manganese concentration in the groundwater must not exceed the groundwater standards for
manganese contained in R 323.2222(3)(f). If nitrate is used to enhance the biological activity of
petroleum degradation, the nitrogen concentration in the groundwater must meet the criteria
contained in R 323.2222(2). If bioremediation is used to remediate organic constituents, the
biological activity should not change the redox conditions such that the metals are stripped from
the soil particles and suspended or dissolved in the groundwater at concentrations above the
standards found in R 323.2222(5)(a).
Note that except where specifically noted, compliance with the R 323.2222 standards is
measured in the groundwater. R 323.2224(1) states that the MDEQ shall approve a
groundwater monitoring location for determining compliance with the standards of R 323.2222 if
the location provides a practicable and effective point of measurement, is located on property
owned or leased by the discharger and under the discharger's control, and is not more than
150 feet from the point of discharge. The MDEQ may approve, under criteria listed in
R 323.2224(2)(a), an alternative groundwater monitoring location up to 1,000 feet hydraulically
downgradient of the discharge to determine compliance with R 323.2222 when part of the RRDapproved remedial investigation , feasibility study, remedial action, corrective action plan, or FAR.
RRD Operational Memorandum No. 4 ,
Attachment 9, In Situ Remedial Discharges
34 of 34
Interim Final
December 2008